World is a highly common name for the planet Earth. But it was originally used to mean the sum of human civilization living on it, specifically human history. In a metaphysical context, World may refer to the Universe, everything that constitutes reality.
‘World’ distinguishes the entire planet or population from any particular country or region. World affairs are those which pertain not just to one place but to the whole world. World history is a field of history which examines events from a global perspective. ‘World’ can also be used attributively, as an adjective, to mean ‘global’, forming usages such as World community. By extension, a ‘world’ may refer to any planet or heavenly body, especially when it is thought of as inhabited.
‘World’, in its original sense, when qualified, can also refer to a particular domain of human experience.
The world of work describes paid work in social aspects. The fashion world describes the environment of the designers. The Old World refers, by contrast, to the continents of Europe, Asia and north Africa. The New World is a part of the world discovered or colonized by Europeans later than other parts.